Environment-Friendly Zinc Oxide Nanorods-Grown Cellulose Nanofiber Nanocomposite and Its Electromechanical and UV Sensing Behaviors.

Jaehwan Kim,Muhammad Latif,Hussein Alrobei,Rizwan A. Malik,Hyun-Chan Kim,Lindong Zhai,Ruth M. Muthoka

doi:10.3390/nano11061419

Abstract

This paper reports a genuine environment-friendly hybrid nanocomposite made by growing zinc oxide (ZnO) nanorods on cellulose nanofiber (CNF) film. The nanocomposite preparation, characterizations, electromechanical property, and ultraviolet (UV) sensing performance are explained. CNF was extracted from the pulp by combining the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation and the aqueous counter collision (ACC) methods. The CNF film was fabricated using doctor blade casting, and ZnO nanorods were grown on the CNF film by seeding and by a hydrothermal method. Morphologies, optical transparency, mechanical and electromechanical properties, and UV sensing properties were examined. The nanocomposite’s optical transparency was more than 80%, and the piezoelectric charge constant d31 was 200 times larger than the CNF film. The UV sensing performance of the prepared ZnO-CNF nanocomposites was tested in terms of ZnO concentration, UV irradiance intensity, exposure side, and electrode materials. A large aspect ratio of ZnO nanorods and a work function gap between ZnO nanorods and the electrode material are essential for improving the UV sensing performance. However, these conditions should be compromised with transparency. The use of CNF for ZnO-cellulose hybrid nanocomposite is beneficial not only for electromechanical and UV sensing properties but also for high mechanical properties, renewability, biocompatibility, flexibility, non-toxicity, and transparency.

Highlights

Organic and inorganic functional nanocomposites combine advantages of the individual materials that surpass parental material properties
The pristine Cellulose nanofiber (CNF) film showed the highest transparency of 89.2% in the visible light range, and the ZCNs exhibited high transparencies of 82.9% and 80.7% for the 25 mM and 50 mM zinc oxide (ZnO)
The vertically grown ZnO nanorods are beneficial for improving optical transparency and electromechanical properties

Summary

Introduction

Organic and inorganic functional nanocomposites combine advantages of the individual materials that surpass parental material properties. They can achieve high mechanical strength, electrical conductivity, thermal conductivity, antibacterial, gas barrier, flame retardancy, electromagnetic shielding, optical transparency, energy harvesting, and actuating properties [1]. Cellulose nanofiber (CNF) is an outstanding organic material composed of nano-sized cellulose fibrils with a high aspect ratio [2,3,4,5,6,7]. CNF extracted from plants by the top-down approach has excellent properties: renewability, biodegradability, abundance, low price, and light weight and high optical transparency, outstanding mechanical properties, and low thermal expansion coefficient [6].

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